This is exactly the kind of hidden issue I was worried about! Does anyone know if there are similar traps for retirement accounts in your home country? I have something similar to a 401k back in my country.

For retirement accounts, it depends on the country and whether there's a tax treaty that provides specific provisions for retirement accounts. Some countries have treaties that allow certain foreign retirement accounts to maintain tax-deferred status in the US, similar to how a 401k works. For example, the US-UK tax treaty recognizes certain UK pension schemes. Without a treaty, your foreign retirement account might be treated as a regular investment account or possibly even as a PFIC or foreign trust, which comes with complex reporting. I'd recommend checking if there's a tax treaty between the US and your home country with provisions for retirement accounts.

The day counting rules are so confusing! Do business trips count the same as vacation days? And what about if you're just connecting through a US airport on the way somewhere else?

Business trips and vacation days both count the same for the substantial presence test - any day you're physically present in the US counts as a day (with some rare exceptions like if you're unable to leave due to a medical condition that developed while in the US). For airport connections, if you're just transiting through the US and don't actually go through immigration and enter the country (staying in the international transit area), then those days don't count. But if you do go through US immigration even just for a connecting flight, that day counts as a US day for the substantial presence test.

Our title company refused to handle this when we had a lien. They required a full release before closing. Maybe it varies by state or company?

Don't you still have to report and reconcile the Advance Premium Tax Credit though? I don't think skipping it is even an option if you received APTC during the year, is it?

You're absolutely right. If you received advance payments of the premium tax credit (APTC) during the year, you must file Form 8962 to reconcile those payments regardless of which approach you take. What I meant was calculating your taxes both ways - taking the full PTC you're entitled to and deducting only premiums not covered by the PTC, versus repaying the APTC you received and deducting your full premiums as self-employed health insurance. But reconciling the APTC is mandatory either way.

I used TaxSlayer last year with a similar situation. You need to first complete the entire ACA/1095-A section with all your information from the Marketplace. Then when you get to the self-employed health insurance section, only enter the amount you actually paid out-of-pocket ($3,240 in your case). TaxSlayer isn't super clear about this but it does work correctly if you enter it that way.

I don't think there's any debt involved with this laptop - he paid for it outright when he bought it. Are there other "benefits" besides debt relief that could make this look like a disguised sale to the IRS? The partnership would just be using the laptop, not paying him anything or giving him extra equity.

There are a few other scenarios that could trigger disguised sale treatment. If the partnership is going to make distributions to the contributing partner within a short period after the contribution, the IRS might view these as connected transactions. Another issue would be if the partnership is assuming any obligations related to the laptop (like a service contract). In your case, it sounds straightforward with no debt, no distributions, and no additional equity, so you're likely fine. But it's always good to document the business purpose for the contribution in your records to show it's not part of a disguised sale arrangement.

I used TurboTax Business last year and it did walk through contributed assets. Make sure you enter the original cost basis of the property when prompted, not the current fair market value. The software should guide you through Section 704 compliance and creating the right asset entries.

Does CashApp Taxes have an option to include a written explanation with your tax return? I have a similar issue but with Etsy sending me a 1099-K for personal items I sold at a loss.

Yes, CashApp Taxes does have an option to add explanations or notes to your return. When you're in the final review stage before filing, there should be a section for "Additional Information" or "Notes" where you can add explanations for unique situations. For your Etsy situation, you'd want to note that these were personal items sold at a loss, not a business activity, which is similar to the original poster's reimbursement scenario. CashApp Taxes isn't as robust as some paid options, but it handles most common situations pretty well if you know where to look for these features.

I've tried both TurboTax and H&R Block for this exact issue. TurboTax actually has a clearer interface for handling incorrect 1099-Ks. It lets you specifically mark personal payments vs business income. H&R Block works too but requires more clicking around to find the right options.